Apparatus for winding helixes



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Patented Aug. 26, 1947 2,426,522 APPARATUS Fon WINDING HELIXEs Charles Benjamin Albert Porter, Hillingdon, England, assigner to Heathway Engineering Company Limited, Hillingdonv Heath, England, a company of Great Britain Application January 10, 1945, Serial No. 572,111

In Great Britain January 17, 1944 (Cl. M-71.5)

21 Claims. 1

This invention relates to apparatus adapted to wind a helix of wire onto one or more longitudinal supports to form an electrode structure for an electron discharge tube, the apparatus being of the kind adapted to form a work-piece consisting of a succession of helixes spaced apart along one or more continuous supports which are subsequently cut up to yield separate electrode structures. The invention is concerned with such ap-` paratus which includes a headstock through the hollow spindle of which the supports are drawn by a gripper constrained to rotate in unison with the headstock spindle, while the wire is fed from a non-travelling guide into engagement with the supports land around a former xed to the end of the spindle nearer to the gripper, the speed of longitudinal movement of the gripper being cyclically varied so as to cause the formation of a succession of helixes of' relatively closely pitched turns spaced by lengths over which the turns are omitted or relatively widely spaced and subsequently removed. Apparatus having the features hereinbefore set out will be termed in the following description and claims apparatus of the kind specified. In such 4machines it is usual to provide, in association with the headstock, tools which nick the Supports at uniform intervals to receive the wire and thereafter'swage over the lips of the nicks to retain the turns of the wire securely anchored to the supports. Y

An object of this invention is to provide apparatus of the kind specied in which the pitch of the helix can be accurately maintained and easily varied by small increments between Wide limits while the length of the supports in the intervals between individual helixes can be given any desired value.

A further object is to provide such improved apparatus which is capable of readily producing electrode structures having a non-uniform helix, such as are used for example as control grids in variable-mu valves.

Another object is to provide apparatus which will full either or both of the foregoing objects and which is compact in relation to the length of a work-piece that can be made in each run of the apparatus.

Another object is to provide in apparatus of the kind specified improved means for supporting the nicking and swaging tools.

Another object is to effect automatically longitudinal relative displacement of the nicking and swaging tools simultaneously with the variation in pitch of a non-uniform helix.

Another object is to provide means Which will automatically deform one or more of the supports in predetermined positions relative to the helixes, the deformations serving to assist in locating the electrode structure in mica spacers or equivalent elementssin an electrode assembly in which the helical grid structure is to be finally incorporated.

Where the gripper is moved longitudinally by a nut engaging a lead screw and the length of the work-piece is not an integral multiple of the pitch of the lead screw, the nut will not register with the lead screw when the gripper is indexed back at the end of one run of the machine in readiness to begin the next run. Consequently the rst helix of the work-piece is liable to be inaccurately pitched, and another object of this invention is to overcome this difficulty.

Further objects and advantages of the invention will be apparent from the following description of two embodiments thereof, given by way of example with reference to the accompanying drawings, in which:

Fig. 1 is an elevation of a portion of one form of Work-piece, which the said embodiments are adapted to make,

Fig. 2 is a diagrammatic front elevation of an elementary form of the improved apparatus,

Fig. 3 is a similar elevation of a preferred embodiment,

Figs. 4 and 5 are end elevations of chain transmissions taken on the lines 4 4 and 5 5 respectively in Fig. 3,

Fig. 6 is a detailed sectional end elevation to a larger scale of means for supporting and actuating the nicking and swaging tools, taken looking l towards the headstock end of Fig. 3,

- Fig. 7 is a plan of the parts shown in Fig. 6, Fig. 8 is a sectional plan, taken on the line -8 in Fig. 6,

Fig. 9 is a front elevation of parts seen at the i righthandend of Fig. 8,

-v headstock axis,

Fig. 13 is a plan of a deformation of a support,

Fig. 14 is a front elevation of a carriage forming part of the machine shown in Fig. 3,

Fig. 15 is a section on the line I5-I 5 in Fig. 17,

Fig. 16 is a section on the line lB-l in Fig. 17,

Fig. 17 is a section on the line I'I-I'l in Fig. 14, and

Fig. 18 is an electrical circuit diagram.

The machine shown in Fig. 2 has a frame I0, carrying a common driving member in the form of a lay-shaft `I I extenoling from end to `end o f the machine vand driven by speed-reducing gearing I2 from a motor I3. A headstock spindle I4 is connected by chain gearing I5 to the lay-shaft II and rotates continuously while .the machine is in operation, carrying on spools I6 the two lengths of support -wire I'I which pass throughgthe spindle I4 and lie respectively in two .grooves 4in a rotat.- ing former I8.

A hollow shaft I9 ending in a gripper 20 is coaxial with the headstock spindle and is slidable in, but constrained by a key 2| to rotate with, -a bush 22 journalled in a stationary housing 23 and rotated by chain gearing 24 in unison with, t-he headstock spindle I4. The ends of the support wires `VI are fixed to the gripper .20, and a split nut 25 is lfixed to the otherend of the .gripper shaft 2 0. T-he bush 2.2 forms the first input .element `of a screw-and-nut differential gear.

A lead screw 26 `is eng-aged with the nut r25 and is formed on -a shaft 2I which is slidable to a limited extent in, but constrained byfakey 2.8 .fto rotate with, a sleeve 29 which in turn is rotatable but not slidable in a bearing 30 on the frame i0. The sleeve `2-9, which forms the second input element of the differential gear, is associated with a brake 3| engageable by a solenoid 3,2. A chain gearing 33 connects the sleeve 20 to the lay-'shaft I I through afriction clutch loaded by va spring 34, which tends to rotate the sleeve :29 in unison with the headstock spindle I4. A spring 35 compressed between the inner end of the sleeve I29 and a flange 3.6 on the shaft2-l normally maintains this shaft in the position shown, `in which a -head v3l on the shaft abuts the outer en d of the sleeve. The sleeve A 2 9 is also connected to the lay-shaft I I through a gear train 38, 39, 40 and a free-wheel clutch `4I of the wedging-roller type. The 'wheel 4 0 is journalled on the shaft `I I and rigid with one element of the clutch 4I. The other element o f this clutch iskeyed to the. shaft vl-I. rThe gear train is arranged after the manner of the screwcuttinggearing of a lathe and thus Yprovides ;.f.0r any desired variation in ratio; the possible ratios are however such that the highest ratio, in thesense from the lay-shaft to the sleeve v.'29, is ylower than .that Gf the power nath thl'vugh the .frCtQn clutch. The f reewheel clutch 4| prevents the wheel y4I] from overrunning theshaft I I in the forward direc-tion. vThe arrangement is therefore such that the lchain gearing 33, operating through the friction clutch, tends to drive the sleeve 29 at headstock-spindle speed, the gear train 38, 39, 40 causes the clutch to slip and limits the speed to any selected value, and the sleeve can be instantaneously stopped `on application of the brake 3l, whereupon the HCB-Wheel 4.] OVCI'.- runs and the slip in the friction clutch rises to 100%.

The heli-X wire .42 is fed from a spool (not shown.) over a non-travelling guide pulley `43 into the nicks cut in the support wires .I'I by a knife 44, and the nicks are thereafter swaged over by a tool 45 in order to lock the helix wire in them. The knife and swaging tool are mounted respectively on two levers 4 6 Vand 41, conveniently pivoted on the lay-shaft I I and actuated by cams 48 and 49 on a camshaft 50, the cams serving to move the tools 4.4 and 45 from their operative to their inoperative positions as required. The camshaft is driven by a pawl 5I mounted on an eccentric 52 on the lay-shaft II and engaging a ratchet wheel 53 on the cam-shaft. A cam 54 on the cam-shaft actuates a switch 55 which controls the brake solenoid 32. The cam-shaft rotates {exactly'one revolution while the .gripper travels a dista-nce equal to the length of a helix plus the length of an interval between heliXes.

As an example of operation of the machine, it will be assumed that the lead-screw pitch is 0.200 in. and that the gear wheel 38 on the sleeve has 50 teeth while the gear wheel on the lay-shaft has 49 teeth. While the brake 3| is off, the sleeve 23 and -the lead-screw 26 are driven through the friction clutch, but their speed is limited by the free-wheel l4I and gear train 38, 33, yl0 to 453-59 .of headstock-spindle speed. The differential speed ofthe nut 25 and the lead-screw 26 is therefore l revolution in 50 of the spindle I4, so that the -gripper is moved 0.200 1/5 0 in. per revolution o f the spindle. |The length of each individual hel-ix and of the intervals between helixes can be readily lvaried by varyingthe effective dwell of the brake-actuating cam54, e. g. by adjustment of a cam-follower (not shown), and the speed of the cam-shaft relative to spindle speed.

When it is desired vto wind heliXes of Vnon-uniform pitch, the lead-screw y26 is reciprocated longitudi-nally with respect to the sleeve 29 by a camfollower vlever 56 engaging the flange 36 and op'- erated by a cam 51 of suitable profile on the camshaft 50. The longitudinal movement of the leadscrew is superimposed on the basic pitch ofthe helix and recovered in the intervals 4between helixes; and alterations may be made in this cam without affecting the basic pitch `or the length of theintervals. The lever -56 may be pivoted von an eccentrically mounted pin `53 which can b e rocked by a handle A50 in order to bring the cam `5l into and out of operation.

In Fig, 3, which shows a preferred embodiment of the invention, parts ycorresponding or equivaient in function to those hereinbefore described with reference to Fig. 2, are denoted by the saine reference numerals respectively, withl the addition of reference letter A. For convenience in illustration, the various shafts are displayed in developed view in Fig. 3; ,'Figs. 4 and show their actual relative positions.

The layshaft IIA drives the headstoek spindle IIIA by a triangular chain drive I5. A which includes a sprocket 60 fast on an eccentric Vshaft 6I provided with a pair of .eccentrics 52A operating a pair of pawls 5 IA which drive the ratchet.

wheel 53A fast on the earn-shaft 50A.

yThe gripper shaft I9A is journalled in a carriage 62 which is supported by the lead-screw shaft 21A and a shaft 63 rotatable in fixed bearing members 64 and 6 5. One end of the leadscrew shaft 21A is supported in the bearingmember 64, and near its other end it passes through the ,Sleeve 29A which is rotatable Yin the bearing' member 6 5 but prevented from sliding. The shaft 21A can be slid througha limited distance and is y.drvably connected to the sleeve 29A by Ythe key 28A. A sleeve 66 is rotatable in bearings in the carriage `62 and slides on the shaft 63, being `constrained to rotate with this shaft by a key 61. A gear-Wheel 3.3 rigid with the sleeve l66 is in constant mesh with a gear-wheel 69 rigid with the gripper shaft ISA. A chain sprocket I0 fast on the shaft 63 is connected by a chain 1I to a sprocket 'I2 fast o n the layshaft IIA. This chain transmission also includes two idler sprockets 'I3 and 'I4 and a fricscrew 26A. A gear-wheel 11 driving the sleeve/l 16 is in constant mesh with the gear-wheel 69. The sleeve 16 is rigid with a body 18 in which are two half nuts 25A radially slidable into and out'of engagement Vwith the lead screw 26A under control of a striking ring 19.

A gear wheel 80 fast on the lead-screw shaft 21A is drivably connected through an idler wheel 8| with a gear wheel 82 rotatable on'the end of thershaft r|53 and connected to this shaft by the free-wheel clutch 4|A. The gear train 80, 8|, 82 is so arranged that the ratio provided -between the shafts 21A and 63 can be easily'varied by changing the gear wheels or otherwise. 'I'he size of the sprocket 15 that is frictionally mounted on the sleeve 29A is such that the friction clutch tends to drive the lead screw 26A at the same speed as the carriage sleeve 16 is driven through the carriage gear-wheel train 68, 69, 11, the shaft 63 and the sprocket 10; the ratio of the gearwheel train 80, 8|,` 82 is such that the free- -wheel clutch 4 IA will operate to reduce the speed of the lead screw and thus cause the carriage to be fed slowly to the right when the nut 25A is engaged and the brake 3IA is released.

It will therefore be evident that this screwand-nut differential gear has its input element 16 connected to the common driving member I IA by the transmission path 12, 1|, 10, 63, 68, 69 and 11, while its input element-29A is connected to the common driving member IIA by two transmission paths in parallel, one of these paths being 12, 1|, 15 and the other 12, 1|, 10, 4|A, 82, 8|, 80, 21A. The output movement of the differential gear is` the longitudinal sliding of the carriage and gripper, which is fast or slow according as the brake 3IA is applied or released. The general mode of operation is accordingly the same as that of the example shown in Fig. 2, but the over-all length of the machine, relative to the length of work-piece, is substantially reduced.

The lead-screw shaft 21A is located in the axial direction by a lbidirectional thrust bearing 36A, 83 which connects this shaft to an arm S4 having at its lower end a nut 85 engaged on a screw 86 formed on a shaft 81 slidable in bearingsin the frame IIIA. The shaft 81 is urged to the left by the compression spring 35A and can be displaced to the right by the cam-follower lever 56A so as to superimpose on the movement of the carriage, due to the differential gear, a movement varying the pitch of the helix being wound by the machine. The shaft 81 can be rotated by a tool applied to its end 88 for the purpose of giving a ne adjustment to the position of the carriage. The range of longitudinal movement of the lead-screw shaft is insufficient to cause the gear-wheel 80 to slide completely out of mesh with the gear-wheel 8 I When a helix of varying pitch is being wound, it is necessary to displace the swaging tool longitudinally with respect to the nicking knife in such a manner that the longitudinal interval between the two is kept equal to one-half of the pitch of the last turn of the helix. Means for obtaining this result are shown diagrammatically in Fig. 3. The lever 41A that carries the swaging tool is rigid with' a shaft 89 slidable in bearings -90 in the frame. A compression spring l9| urges this shaft to the right, and a cam '92 fast on the cam-shaft 50A operates through a bell-crank cam-follower lever 93 to impart to the shaft 89 and the swaging tool 45A the necessary cyclical displacement. The camfollower lever 46A that carries the nicking knife is mounted on the shaft 89 by means of two Y, bearings 94 and 95 and is both slidable and rotatable on this shaft. A compression spring 96 urges the lever 46A to the right, and this lever is located by a bell-crank lever 91 one arm of which engages the bearing 95 and the other arm of which reacts against an adjusting screw 98. This screw enables the knife 44A to be adjusted longitudinally of the machine.

A preferred practical design of the means for controlling the nicking and swaging tools is shown in Figs. 6, '7, 8 and 9. The swaging tool 45A (Figs. 6 and 7) is rotatable on pivot bearings in a bracket 99 having a cylindrical shank |00. This shank is normally clamped fast in a lever head |0I by means of a pinch screw |02. When the pinch screw |02 is slackened, the bracket 99 can be adjusted both transversely with' vrespect to the axis of the headstock spindle [4A by means of a lead screw |03 having a micrometer head I 03', and angularly about the axis of the shank |00, in order to suit different helix angles, by means of a plate |04Ywhich has a bearing 'on the shank |00, which is slidably engaged with a pin |05 rigid with the bracket, and which' can be locked in various angular positions about the axis of the shank |00 by a bolt |06 engaging the head |0I. A Vernier scale of angle |01 is provided between the plate |04 and the head ||l|.v The lever 41A is provided with an upwardly directedA cylindrical pin |08 engaged in a socket portion |09 of the head IUI. A screw ||0 in the socket portion |09 co-operates with a groove I I I on the pin |08 to maintain the axis of the tool A parallel to the headstock axis, and a screw |I2 co-operates with' an inclined notch I3 in the pin |08 to lock the lever head I 0| tightly down against the upper end of the lower proper.

The lever 46A carries the nicking tool 44A by the agency of a similar lever head I I4. This construction facilitates renewal of a nicking or swaging tool, if necessary, while a work-piece is still in position and partly wound. A tension spring I connecting ther levers 46A and 41A constrains them to follow their respective cams 48A and 49A.

The lever 41A is clamped by a pinch bolt I|5 to the shaft 89, which' is slidable and rotatable in the fixed bearings 90 (Fig. 8). The spring 9| is compressed between a head I I6 on the shaft 89 and a thrust bearing |I1 reacting against one of the bearings 90, so that the shaft 89 and the lever 41A'are urged to the right. An adjustable tappet IIB on the right-hand end of the shaft 89 engages the follower lever 93 of the cam 92. The limiting position of this cam-follower lever is determined by a screw stop I I9 (Fig. 9). y

The lever 46A that carries the nicking tool has, as already described with reference to Fig. 3, two bearings 94 and '95 rotatable and slidable on the shaft 89. This lever is urged to the right, relatively to the lever 41A, by the spring 96 which is compressed between a nut |20 on the shaft 89 and a thrust bearing 2| which reacts, through pins such as I 22, slidable through the housing of the bearing 90, and another thrust bearing |23 against the lever bearing 94. The lever 46A is longitudinally located by th'e adjusting screw 98 which sets the bell-crank lever 91. AV thrust bear ing |24is interposed between the lever 91 and the switch 55. This switch replaces the switch 55A l in Fig. 3 and the arrangement enables the separate switch-actuating cam 54A to be omitted.

The means for making the wing deformations |25 (Fig. 1) `in the supports l1 are shown in Figs. 10, 111A and 12. The former I8A is omitted from Fig. 11. The nose of the headstock spindle |4A is fitted With a collet chuck consisting of a foursegrnen-t collet |26 and a flanged actuating nut |21. The former [8A (Figs. 10 and 12) has a cylindrical shank I8 provided with diametrically opposed longitudinal grooves |28 accommodating the supports and each interrupted by a wingforming recess |29. A pair' of wing-forming punches |30 are slidable in radial bores |3| in the spindle head and are provided with heads |32 of rectangular section located in a groove |33 in the spindle nose, so that the Apunches are prevented from rotating in the bores |3-I. A washer |34 is ixed by screws such as |35 to the spindle nose and ,is provided with tongues such as |33 which are bent over to engage in stepped parts I 31 of the punch heads and so limit their' outward movement, these tongues passing through notches such as |38 in the spindle nose.

A headstock bearing housing |39 is provided with a lateral Vextension |40 in which is slidable a striker bar |4| between the retracted position shown in full lines and an extended position which -is shown in chain-dotted lines and which is such that the bevelled end |42 of the bar will strike the punch heads |32 as the headstock spindie rotates and .so cause the punches |30 to indent the supports I1. The bar I4I is moved to its extended position by a vertically slidable cam member |43 having a bevelled end |44 co-operating with a bevelled step I 45 on the bar |4| which is retracted, when Athe member |43 is lowered, by a leaf spring |46. Fig. 13 is a plan of an indented portion |25 vof one of the supports I1, as seen looking towards the headstock spindle axis. The member |43 is actuated by a solenoid |41 biased by a compression spring |48 and connected by a link |49 and a lever |50 to the member |43. The solenoid |41 is momentarily energized, once during each cycle of operation f the cam-shaft 511A, through a switch I| actuated by a cam I 52.

It has hereinbefore been mentioned that, when the length of work-piece being wound in a run of the machine is not an integral multiple of the pitch of the lead screw 26A, it is necessary to make special provision toensure that the first helix orf-the series of helixes constituting one completed work-piece has the proper spacing of the first few turns. Means for attaining this object will be described with reference to Figs. 14-18. Figs. 14-1'7 show a practical design of the carriage illustrated diagrammatically in Fig. 3. Since the same reference numerals are employed to denote the principal parts of the carriage vin these figures, the general design shown in Figs. 14-17 will be clear.

Referring to Fig. l5, the gripper A includes -two jaw levers |53 pivoted on two pins |54 spanning a longitudinal slot in the gripper shaft ISA. These jaws are urged open by a compression spring |55 and can 'be closed to grip the supports by movement to the right of a tension rod |56 under the influence .of a compression spring |51. A cagm |53 pinned on a control shaft |59 has a lobe` |60 .co-,Operating with the end of the pull rod |55` and a lug IGI. Displacement of the cam` in the counter-clockwise direction is limited by a stop pin |32 fast in the carriage body 62 and co-operating with the lug I 6 The control shaft |59 is rotatable in bearings |33 and |53 (Fig. 17) on the carriage body by means of a handle |54 pinned to the shaft. A torsion spring |55 surrounds a part of the shaft |59 and has its ends anchored respectively in the bearing |63 and in'a collar |55 pinned to the shaft |59. This spring biases the shaft towards the counter-clockwise limit of its range of movement, as viewed from the handle end.

The split nut (Fig. 16) includes a nut housing 18 (shown sectioned on the line I5-18 in Fig. 1'1). This housing consists of a flange |61 Which is integral with the sleeve 13 and a cover portion |58 which is fixed to the ilange |61 by screws (not appearing in Fig. 1G). A knurled ring |69 is rotatably mounted on the nut housing, being retained by a washer |1|l which is secured to the part |68 by screws such as |1|; this washer engages an internal flange |12 which is formed on the ring |69 and which surrounds a reduced end of the part |38. Each half nut 25A is guided for radial sliding betweenV` the parts |31 and |158 and is urged radially inwards by a compression spring |13 which reacts against a strip |14 of friction material located in a longitudinal groove in the nut body 18 and urged by the spring |13 against the inside of the ring |59 which is thereby frictionally clutched to the nut body. The gear wheel 11 is coupled by a key |15 to a, ratchet wheel |16, this wheel cluster being rotatable on the sleeve 15. The ratchet wheel |15 is accommodated in a counterbore in the flange |61 and a pawl |11 radially slidable in this flange co-operates with the ratchet wheel, being urged inwards by a wire cantilever spring |18 held by a screw |19 (Fig. 14). The free-wheel constituted by the ratchet wheel |16 and the pawl |11 normally transmits the drive from the gear wheel 11 to the nut. The striking ring 19 for opening the nut has two diametrically opposed pairs of longitudinal prongs provided with bevelled ends; each pair cooperates with the ends of a pin |8| passing through the corresponding half nut 25A. When the striking ring 19 is moved to the left from the position shown, the pins I 8| are caused to ride up the bevelled ends of the prongs |80 and so disengage the half nuts from the lead screw 26A. The striking ring 19 is actuated by a yoke 82 rotatable on the control shaft |59 and having striking pins |83 co-operating with a groove |84 in the striking ring. f A pin |85 fast in the yoke |32 co-operates with the lug |6| on the control shaft cam. Movement of the striking ring to the right beyond the position shown in Figs. 14 and 16 is prevented by engagement of the pin |85 with a xed pin |86 (Fig. 15).

Displacement of the carriage to the left is limited by engagement of a nut |81 on the leadscrew sleeve 16 with the lead-screw bearing 64 (Fig. 14). A switch-operating plunger I 88 is slidable in the housing of the bearing 64 and its head normally projects as shown, so that the plunger is depressed as the carriage is stopped against the face of the bearing 54. The plunger |88 o-perates normally-closed contacts A and B shown in Fig. 18, where I is a relay provided with a push button P and II is a relay controlling a con-tactor III for the main driving motor I3.

The operation of the machine is as follows. While the machine is running normally, the carriage control handle |64 (Figs. 14 and 17) is at the counter-clockwise limit of its range of movement, the gripper 2BA being closed and the half nuts Y25A engaged with the lead screw 26A. The' electrical control system is in the condition shown in Fig. 18: relay II is energised by a circuit fromy positive through contacts B, back contacts of relay I and coil of relay II to negative, the motor contactor III being energised by a circuit from positive through front contacts of relay II and coil of contactor III to negative. When the last helix of a series constituting a complete workpiece has been wound, push-button P is pressed, breaking the energising circuit of relay II which releases and causes the motor contacter III to open. A hold-on circuit for relay I is established from positive through back contacts of relay II,.

contacts A, front contacts of relay I and coil of relay I to negative.

Next the work-piece is separated from the headstock by a guillotine (not shown), and the carriage control lever |64 is urged clockwise to the position shown in Figs. 14 and 15 so that the gripper 20A is opened; the work-piece is then removed. Next Ythe lever |64 is urged more strongly clockwise so as toA force thet striking ring 19 to the left and open the half nuts 25A. As soon as these half nuts are disengaged from the lead screw 26A, the pressure of the operators hand on the leverl |64 causes the carriage to move to the left until it isv stopped by abutting of the nut |81 against the bearing 64. The ends of the supports are now betweenthe jaws of theY gripper which close when the handle |64 is released. Depression of the switch plunger |88 opens both contacts A and B (Fig. V18) substan-l tially simultaneously. Opening of contacts A interrupts the hold-on circuit of relayI, which reverts to the condition shown. Relay II remains unoperated, since contacts B are open.

Though the 4striking ring 19 is now free Vto slide to the right as the half nuts 25A are urged inwards by their springs, owing to lack of registration between the nut and the lead screw the half nuts will usually not' immediately engage. The operator accordingly rotates the knurled ring |69in the normalY direction of rotation of the nut, and the free-wheel |16, |11 allows the sleeve 16 and the nut body 18 to be rotated, as aV result of the frictional drag imposed by the strips |14, until the half nuts are fully engaged with the lead screw. On continued rotation of the knurled sleeve, the frictional drag transmits suicient torque to the half nuts to cause the nut body 18 and the sleeve16 to begin tol move` to the right, e. g. to the extent permitted by aslight end play between the sleeve 16 andthe carriage body 62. Such axial movement of the sleeve 16 is sufficient to allow contacts B to close while leaving contacts A open. Thereupon theV circuit is closed from positive, through contacts B, back contacts of relayI and coil of relay II to negative, relay II operates and the motor contactor III is thereby closed. 'I he machine is thus started on its next run, and, as the carriage begins its traverse, contacts A close, leaving the velectrical system in its initial condition. v Relay I may be arranged to operate with a short delay, so as to` prevent accidental starting of thefmotor if the carriage is brought against the Vstop so slowly that contacts A open an appreciable time before contacts B. The carriage may be arranged to operate a switch plunger |39 (Figs. 15 and 18) as it reaches the right-hand end of its run, which closes contacts C and thereby automatically opcrates relay I. .nl Y

last-mentioned means comprise a diierential gear having two input elements, a common driving member drivably connected to both of the said input elements, the connection between one of said input elements and said driving member including speed-changing means, and means operatively connected to said driving member for cyclically changing the condition of said speedchanging means.

2. Apparatus as claimed in claim 1, characterized in that said speed-changing means in one condition arrest the said one input element and thereby cause a relatively rapid longitudinal Vmovement of the gripper, and in another condition rotate said one input element in such a 'manner as to cause a relatively slow vlongitudinal movement of said gripper.

3.n Apparatus as claimed in claim 1, characterized in that the said differential gear has a screw member co-operating with a nut member, and thatone of the said input elements is connected to drive one of saidV differential gear members through said speed-changing means, while the other of said input elements serves to impart uniform rotation to said gripper and to the other of saiddifferential gear members, which is coupled for longitudinal movement with said gripper.

4. Apparatus as claimed in claim 1, characterized in that the Said speed-changing means include twoparallel power' paths between the said common driving member andthe 'said one in- 'put element, and a brake operable for arresting the said one input element, the first of said power paths including a slipable driving connection,

Vwhile the second of said power paths, which has a lower-speed ratio than said first power path,

vincludes a free-wheel arranged to limit the speed of the said one input element to the value determined by the ratio of said second power path and to over-run when said brake isapplied, said second power path being so arranged that its ratio can be varied. Y

5. Apparatus as claimed in claim l, characterized in that the saidrdiflerential gear has a screw member zo-operating with anut member, that one of thesaid input elements is connected to drive one of said differential gear members through'said speed-changing means, while the other of said input elementsV serves to 'impart uniform rotation to said gripper and to the other Yof said differential gear members, which is coupled for longitudinal movement with said gripper, and that thesaid speed-changing means include two'parallel power paths between the said common driving member and the said one input element and a brake operable for arresting the said one input element, the rst of Vsaid power paths including a slipable drivingconnection while the second of said power paths, which has a lowerspeed ratio than said rst power path, includes a free-wheel arranged to limit the speed of the said one input'k element to the value determined bythe ratio of ,said second power path and te ized in that the said differential gear has a screw member co-operating with a nut member, that one of the said input elements is connected to drive one of said differential gear members through said speed-changing means, while the other of said input elements serves to impart uniform rotation to said gripper and to the other of said diiferential gear members, which is coupled for longitudinal movement with said gripper, and that said one differential gear member is longitudinally displaceable, under the control of a Cam driven by said common driving member, such displacement occurring, when desired, cyclically and serving to produce heliXes of non-uniform pitch.

7. Apparatus as claimed in claim 1, characterized by a constant-speed shaft rotatable at a constant ratio with said headstock spindle, a carriage slidable longitudinally with respect to the said headstock spindle along a lead-screw, the said gripper being journalled in said carriage, and the said speed-changing means connecting said lead-screw to said common driving means, a sleeve journalled in said carriage and penetrated by said lead screw, gearing in said carriage drivably connecting said sleeve, said gripper and said constant-speed shaft, and a nut on said sleeve engageable with said lead screw.

8. Apparatus as claimed in claim 1, for winding non-uniform heliXes, characterized by a constantspeed shaft rotatable at a constant ratio with said headstock spindle, a carriage slidable longitudinally with respect to the said headstock spindle along a lead-screw, the said gripper being journalled in said carriage, and the said speedchanging means connecting said lead-screw to said common driving means, a sleeve journalled in said carriage and penetrated by said lead screw, gearing in said carriage drivably connecting said sleeve, said gripper and said constant-speed shaft, a nut on said sleeve engageable with said lead screw, a cam operated by said common driving member, and means actuated by said cam for cyclically varying the location of said lead-screw longitudinally with respect to said headstock spindle. Y

9. Apparatus as claimed in claim 1, characterized by a constant-speed' shaft rotatable at a constant ratio with said headstock spindle, a carriage slidable longitudinally with respect to the said headstock spindle along a lead-screw, the said gripper being journalled in said carriage, a sleeve journalled in said carriage and penetrated by said lead screw, gearing in said carriage drivably connecting said sleeve, said gripper and said constant-speed shaft, a'nut on said sleeve engageable with said lead screw, a power path including a friction clutch connecting said common driving member to said lead screw, a power path of constant ratio connecting said common driving member to said constant-speed shaft, a power path including a free-wheel in series withA a changeable gear trainr connecting said lead screw to said constant-speed shaft and a brake operable for arresting said lead screw by causing- 100 percent slip of said friction clutch and over-running of said free wheel while said constant-speed shaf-t continues to rotate.

l0. Apparatus of the kind specified, for winding a succession of helixes of wire onto at least `one longitudinal support to form. a seriesV f electrode structures for electron discharge tubes, the, apparat-,us including a hollow headstock spindle, a gripper for drawing a support through said spindle, and means constraining saidA gripper and said spindle to rotate in unison, characterized by 4a constant-speed shaft and a lead screw disposed parallel to the axis of said headstock and rotatable in bearings in the frame of the apparatus, a carriage supported by said shafts, the said gripper being journalled in said carriage, a nut journalled in said carriage and zzo-operating with said lead screw, a sleeve journalled in said carriage and constrained to rotate with said shaft, gearing in said carriage for drivably connecting said shaft,fsaid gripper and said nut, a common driving member drivably connected to said headstock spindle and tosaid shaft and a variable-speed transmission connecting said driving member to said lead screw.

1l. Apparatus of the kind specied,y for wind'- ing a succession of heliXes of Ywire onto at least one longitudinal support to form a series of electrode structures for electron discharge tubes, the apparatus including a hollow headstock spindle, a gripper for drawing a support through said spindle, means constraining said gripper and said spindle to rotate in unison and for displacing said gripper relatively to said spindle alternatively at relatively slow and fast speeds, two tools serving respectively for nicking and swaging said support, two levers carrying said tools respectively, and cam mechanism for cyclically displacing said levers so as to maintain said toc-ls in and out of operative positions during the times of such slow and fast displacements respectively, said nicking' tool being a disk rotatable about an axis perpendicularA to a line radial with' respect tothe aXis of said headstock spindle, characterised in that said disc is journalled in a holder so mounted inthe appropriate one of said levers as to be angularly adjustable about said radial line. Y

Y 12. Apparatus of the kindV speced, for winding a succession of non-uniform helixes of wire onto at least one longitudinal support to form a series of electrode structuresv for electron discharge tubes, the apparatus including a hollow headstock spindle, a gripper for drawing a support through said spindle, means constraining said gripper and said spindle to rotate in unison and for displacing said gripper relativelyto said spindle alternatively at a speed which is relatively slow and. non-uniform and at a relatively fast speed, two tools serving respectively for nicking and swaging said support, two levers carrying said tools respectively, and cam mechanism for cyclically displacing said levers so as to maintain sai-d tools in and out of operative positions during the times of such slow and fast displacements respectively, characterized inA that the one of the said two levers that carries said swaging tool is rigid withv a pivot shaft parallel to said headstock spindle and capable of rocking and slidingv relatively tosaid headstock, the other of said two levers is slidably and rockably mounted cnsaid pivot sha-ft, adjusting means are provided for axially locating said other lever, and said pivot shaft is axially located by a cam of said cam mechanism, said cam having a shape such as to adjust the longitudinalspacing of said tools as is necessary to accommodate'the Variation inr pitch of the helix. ,l l

13. Apparatusv of the kind specified, for winding a succession of heliX'es of wire onto at least one longitudinal support to form a series of electrode structures for electron discharge tubes, the apparatus including a hollow headstock spindle, a gripper for drawing a support through said spindle and means constraining said gripper and said spindle to rotate in unison, characterized by a constant-speed shaft and a lead screw disposed parallel to the axis of said headstock, a carriage in which said gripper is journalled, a sleeve journalled in said carriage, said sleeve embracing and being constrained to rotate with said shaft, a nut body journalled in said carriage and surrounding said lead screw, gearing in said carriage drivably connecting said shaft, said gripper and said nut body, a nut element displaceable in said nut body between an inoperative position and an operative portion in which it meshes with said lead screw, a striking member for so displacing said nut element, and a common control member `for said gripper and said nut element and serving on continued operation in the same sense firstly to open said gripper and thereafter to displace said nut element to its inoperative position.

14. Apparatus as claimed in claim 13, characterized in that said common control member is so mounted on said carriage that, when it is operated in the said sense, continued pressure of the operators hand on the control member will serve to index said carriage back to its starting position after displacement of said nut element to its inoperative position.

15. Apparatus of the kind specified, for winding a succession of helixes of wire onto at least one longitudinal support to form a series of electrode structures for electron discharge tubes, the apparatus including a common driving member, a hollow headstock spindle, a gripper for drawing a support through said spindle, a disengageable screw-and-nut gear for imparting longitudinal displacement to said gripper, means drivably connecting said spindle and said gripper for rotation in unison by said driving member, a variable, speed transmission connecting said screw-andnut gear to said driving member, a cam-shaft drivably connected to said driving member and actuating cam mechanism for cyclically changing the condition of said variable-speed transmission so as to cause said gripper to be displaced alternatively at slowvand fast speeds, and a clutch which serves, after indexing displacement of said gripper back to its starting position, to permit such ro-tation of an element of said screw-and-nut gearing as is necessary to bring it into register for re-engagement, independently of rotation of said cam-shaft.

16. Apparatus as claimed in claim l5, including means for starting and stopping said driving member, and means responsive to re-engagement of said screw-and-nut gearing for delaying starting of said driving member untilsuch re-engagement has occurred.

17. Apparatus as claimed in claim 15, including means for starting and stopping said driving member, and means for automatically restarting said driving member in response to re-engagement of said screw-and-nut gearing.

18. Apparatus of the kind specified, for winding a succession of helixes of wire onto at least one longitudinal support to form a series of electrode structures for electron discharge tubes, the apparatus including a common driving member, a hollow headstock spindle, a gripper displaceable for drawing a support through said spindle, a lead screw, a nut constrained to be displaced with said gripper and disengageably coupled to said lead screw, power transmission means drivably "I4 connected to said driving'memberffor constrairiing said spindle and said gripper to rotate in unison andv for imparting a rotation to said nut, a variable-speed transmission connecting said driving member to said lead screw, and cam mechanism drivably connected to said driving member for cyclically changingthe condition of said variable-speed transmission, said power transmission means including a free-wheel clutch for permitting said nut to be rotated independently for the purpose of bringing it into register for reengagement with said lead screw after indexing displacement of said gripper back to its starting position.

- 19. Apparatus of the kind specified, for winding a succession of heliXes of wire onto at least one longitudinal support to form a series of electrode structures for electron discharge tubes, the apparatus including a driving member, a hollow headstock spindle drivably connected to said driving member, a lead screw and a shaft parallel to the axis of said spindle, a carriage slidable along said lead screw and said shaft, a gripper co-aXial with said spindle and journalled in said carriage, a power transmission path connecting said driving member to said shaft, a nut body in said carriage surrounding said lead screw and carrying a nut element disengageable from said lead screw, gearing in said carriage connecting said shaft, said gripper and said nut body and serving to rotate said gripper in unison with said spindle, said gearing including a free-wheel permitting said nut body to be rotated in its forward direction when said shaft and said gripper are at rest, a change-speed transmission connecting said driving member to said lead screw, cam mechanism driven by said driving member for cyclically changing the condition of said change-speed transmission, an indexing stop for limiting displacement of said carriage towards said headstock, and control means operable for stopping said driving member and for restarting it, when said carriage is indexed by said stop, in response to re-engagement of said nut with said lead screw effected by forward rotation of said nut permitted by said free-wheel.

20. Apparatus of the kind specified, for winding a succession of helixes of wire onto at least one longitudinal support to form a series of electrode structures for electron discharge tubes, the apparatus including a former, means for feeding said support longitudinally over said former alternately at relatively slow and fast speeds, means Y for feeding a helix wire to said former, driving means for causing relative rotation between said former and said wire-feeding means and thereby applying to said support a succession of relatively closely pitched wire helixes spaced from one another by'intervals occupied by coarsely pitched turns, characterised by a tool co-operating with said former for forming on said support wings capable of locating the electrode structure in an electrode assembly into rwhich it is required to be incorporated, and means including a cam operated by said driving means for actuating said tool to deform said support at points coming within each of said intervals, said tool being inoperative on the parts of said support to be occupied by said closely pitched helixes.

21. Apparatus as claimed in claim 20, wherein said former has a longitudinal groove for said support, characterised in that said former has a wing-formingY recess opening out of said groove, and that said tool is a wing-forming punchmov- '21,499,592 L A Y15 16` 91,1119-Y subs'tantialy radially withV respect 1gov salid UNITE-D STATES PATENTS- f-ormer 53nd cci-Operating with said recess to dey Y Number Name Date form the Support' 1,897,450 Anderson et 51` Feb; 14, 1933 CHARLES- BENJAM-LN ALBERT PORTER; '5 11970599 Franke Aug# 211 1934 1,994,307 Flaws, J1' Mar. 12, 1935 Y 2,181,288 Washburn Nov. 28, 1939 REFERENCES CITED 1,595,905 Madd-en et a1 1 May 25, 1926 The following'y references are of record i`r1 the 1,814,770 lSchenk et a1 July 14, 1931 me off this pacen'cz' 10 1,974,575 Morick et 51 Aug. so, 1932 

